package com.chinasofti.bufferedio;

public class 学习 {
    public static void main(String[] args) {
        int arr  [] = {1,2,3,4,5,6,7,8,9};
        int number =  4;
        int i =binarySearch(arr,4);
        System.out.println(i);
    }

    private static int binarySearch(int[] arr, int number) {
        int min = 0;
        int max= arr.length-1;
        while (min<=max){
            int mid = (max+min)>>1;
            if(arr[mid]>number){
                max=mid-1;
            }else if (arr[mid]<number){
                min=mid+1;
            }
            else {
                return mid;
            }

        }
        return -1;
    }

}
